物理中有一类单项选择题,其选项是用函数关系表达,而这种关系又不能立即判断清楚,或者变化趋势不是递增(或递减)的问题,用常规方法一般很难求解或求解过程较为繁琐,我们可以对变量给出一个或二个特值(一般是极大值或极小值),而且这些特值在题目中对应的结构是一目了然的或是通过简单的计算很容易得到的,把它代入选项中进行对照,排除错误的,便可快速求解。 There is a category of single-choice questions in physics. Their options are expressed in functional relationships. This relationship is not immediately clear, or the trend is not an incremental (or decremental) problem. It is generally difficult to solve or the solution process is relatively difficult using conventional methods. In tedious, we can give one or two special values ​​(usually maximum or minimum values) to variables, and the corresponding structure of these special values ​​in the title is very clear or easily obtained through simple calculations. Put it into the options for comparison, eliminate the error, you can quickly solve.